抄録
In the previous report it was clarified that montmorillonite is one of the factors which dominate the susceptivity of mechanical properties of coal measure rocks to the influence of water.
In the present paper discussion is made on the basis of experimental data on two other mechanisms to which the lowered rock strength with increased moisture is ascribed. Firstly, it is shown that adsorption of water reduces the free surface energy, which leads to the decrease in strength of the rocks in thelower humidity range. Secondly, it is made clearthat reduction of capillary tensions with increased moisture can lower the strength of the rocks in the wider range of humidity.
